Cooperation is an unstable strategy. If everyone else is cooperating and not punishing defectors much, defecting is vastly better for you.
If everyone else is defecting and you can cooperate with a few people, that's slightly better for you. Hence we have high-trust and low-trust societies, gatekeeping, etc.
If everyone else is defecting and you can cooperate with a few people, that's slightly better for you. Hence we have high-trust and low-trust societies, gatekeeping, etc.